Car Installation:

1. Go into GTA V in OpenIV. 
2. navigate to update\x64\dlcpacks\mpchristmas2\dlc.rpf\x64\levels\gta5\vehicles\xmas2vehicles.rpf. and make sure Edit Mode 
is activated. 
3. Then find jester2.ytd.
4. Make a backup copy (Extract it).
5. Replace it with jester2.ytd from the Batman Jester Folder.

License Plate Installation:

1. Go into GTA V in OpenIV. 
2. navigate to GTA V\x64e.rpf\levels\gta5\vehicles.rpf. and make sure Edit Mode 
is activated. 
3. Find vehshare.ytd
4. Make a backup copy (Extract it).
5. Replace it with vehshare.ytd from the Batman License Plate folder.
6. Vist LS Customs and buy the Yellow on Black Plate.

I suggest downloading Customize Plate Mod and setting the license plate blank.
Download Link: https://www.gta5-mods.com/scripts/customize-plate